Method and device for feeding of long objects

ABSTRACT

The present invention is for a method and a means for feeding of strip material to working machine in which the material is worked upon and separated into individual parts. Primarily the invention is for feeding of metal strip to presses. At intermittent feeding of long objects ( 3 ) to working machines ( 2 )the feed rate is controlled in relation to the speed of the working machine. The control of the feed rate is by means of a control system having a processor is supplied with signals which correspond to the speed and position of the working machine and the feed rate and fed length of the fed material ( 3 ).

[0001] The present invention is for a method and a means for feeding of strip or band material to working machines in which the goods is worked upon and split up in individual parts. Primarily the invention is for feeding of metal bands to presses for bending, punching and cutting.

[0002] Feeding of material is preferably by means of a roll feeder at which the material is brought forward by two rolls between which and band or other long object is clamped. The rolls operate intermittently so that feeding of material takes place only when the working machine is in a position for receiving the material. Controllable parameters are stops and starts, rate of feeding and length of feeding.

[0003] The roll feeders are usually connected to an working machine for example an eccentric press, hydraulic press or the like. These are often automated and continuously working machines at it is a requirement that the feed in fully agrees with the speed of operation and need for material of the working machine at each individual moment of operation, the feed in has to be synchronised with the working machine. Nor shall the roll feeder work at a higher speed than the process requires as unnecessarily high speed brings with it raised standards of the included components and a greater wear than at correctly adjusted speed. If optimal synchronised operation shall be possible then the roll feeder shall feed the workpiece slowly when the working machine runs slowly and when it works fast the roll feeder shall feed fast. Roll feeders which are under forced control by a mechanical connection with the working machine, for example the eccentric shaft of a press, follow the speed of the working machine but there are great difficulties at the setting of the feed length at a continuous or long workpiece.

[0004] The object of the present invention is at method and a control system at which the feed rate of a material feeding device, for example a roll feeder, automatically adjusts itself relative to the speed of the working machine. The invention is characterized by the features which are mentioned in claim 1. Characteristics of further embodiments of the invention are given in the depending claims.

[0005] The invention will below be described more in detail with reference to the embodiment which is shown in the enclosed FIGURE.

[0006] The FIGURE shows a roll feeder and an eccentric press to which material is fed by the roll feeder. The FIGURE is intended to show the principles of the invention, hiding side walls and other details of the construction are not shown in the FIGURE.

[0007] Material in the shape of a continuous strip 3 is supplied to the roll feeder from a storage, a roll or the like. Over the support rolls 9, 10, 11 which are arranged in a bowshape within the supporting lane 1 the material is fed in between the feed rolls 4 and 5 and further on to an excenter press 2. The distance between the roll feeder and the excenter press is often much smaller than as shown in the FIGURE. Den upper feed roll 4 is forced downwards by means of a pneumatic cylinder or in any other suitable way. The feed rolls are driven by a motor 15 which works on the lower feed roll 5, the upper feed roll 4 is driven by the lower feed roll 5 by means of gear wheels. A measuring wheel 8 having a first pulse transmitter 14 is arranged adjacent to the feed rolls and in known manner it produces pulses relative to the length and speed of the feeding of material. The measuring wheel is forced downwards against the strip of material which underneath is supported by a lower support wheel or support roll 12. Preferably the measuring wheel is arranged ahead of the feed rolls in the direction of conveyance of the material. As an alternative a pulse transmitter 16 may be arranged so that pulses are received directly from the driving motor 15. A second pulse transmitter 7 is arranged so that it delivers pulses relative to the rotation of the eccentric shaft 6. The signals from the pulse transmitters are input into a control system with a processor in which the signals are processed. The signals from the second pulse transmitter are then not only used to determine the position of the eccentric shaft but also to determine its speed of rotation. The first pulse transmitter may give signals which correspond to the speed of the feed strip and the length of fed material during a cycle of operation. Various functions which are controlled by the control system are when feed of material is to be started and when it must be concluded and also various monitoring functions, for example that a part which has been worked upon is removed from the tool of the excenter press.

[0008] In addition to the functions which have been mentioned above the method of the invention also comprises adapting the speed of the feeding of material to the speed of rotation of the eccentric shaft which may be achieved thereby that the number of pulses per unit time from the second pulse transmitter of the control system is compared to the set length of feeding for each cycle of operation. The processor of the control system then calculates the optimum speed of the feed rolls 4, 5. Preferably there have been input to the system limiting values for the feed rate and possibly also other variables. If these limit values are passed various activities may be initiated by the control system, for example alarm, stop and error message to a display which is connected to the system or to a text message monitor.

[0009] The invention is above described with reference to an eccentric press but it is not limited, to this kind of working machines. Other machines with which the invention may find uses are other kinds of presses, punching and cutting machines, bending machines and the like, besides the above described pulse transmitters other transmitters of the same or other kinds may be connected to the control system and these may affect for example the allowed limiting values. 

1. Method by intermittent feeding of long objects (3) to working machines (2) where the feed rate is controlled in relation to the speed of the working machine characterized in that the control of the feed rate is by means of a control system with a processor is supplied with signals which correspond to the speed and position of the working machine and to the rate and fed length of the fed material (3).
 2. Method according to claim 1 characterized in that the control system is supplied with signals from a first pulse transmitter (14, 16) which gives signals from the fed goods (3) or its driving means (15) and a second pulse transmitter (7) which gives signals from the working machine (2).
 3. method according to claim 2 characterized in that the second pulse transmitter (7) gives signals from a driving shaft (6) of the working machine (2).
 4. Method according to claim 3 characterized in that the second pulse transmitter (7) gives signals from the eccentric shaft (6) of an excenter press.
 5. Method according to any of the preceding claims characterized in that the material is fed by a roll feeder (13).
 6. Means for controlling the feeding of material of long or strip material (3) to a working machine (2) characterized in that in comprises a first pulse transmitter (14, 16) from transmission of signals from the fed material or its driving means, a second pulse transmitter (7) for transmission of signals from the driving means of the working machine, a control system having a processor in which the signals from the pulse transmitters is processed so that the rate of feeding is controlled by signals from the controlling system. 